Final answer:
When the temperature of a pottery kiln is increased, the peak of its spectral emittance curve shifts toward higher frequencies and shorter wavelengths, corresponding to an increase in emitted energy at these wavelengths. The correct option is A).
Step-by-step explanation:
When you increase the temperature of a pottery kiln from 800º C to 1200º C, the peak of the spectral emittance curve shifts to shorter wavelengths. This is reflected in everyday observations, such as when metals heated to high temperatures begin to glow red and then transition to white-hot as the temperature increases.
This phenomenon occurs because at higher temperatures, a blackbody (an ideal radiator) emits a greater fraction of its energy at shorter wavelengths (which correspond to higher frequencies and higher energies).
As we understand, an increase in temperature causes the spectrum to shift toward the visible and ultraviolet parts of the spectrum, making the visible appearance of the object shift from red to white and eventually to blue as the temperature further increases.
Therefore, the correct answer to the question would be that the peak of the spectral emittance curve shifts to higher frequencies or shorter wavelengths when the temperature is increased. Option A) is the correct one.